1. Field of the Invention
The invention relates generally to an information recording medium such as a BD-R, an apparatus for recording/reproducing information to/from the information recording medium, and a method for recording information on the information recording medium.
2. Description of Related Art
UDF (Universal Disk Format) is known as a format for recording and managing files in optical discs typified by DVDs and BDs Blu-Ray Disc.
Reference 1 proposes a recording/reproduction apparatus that records a file on a recording medium in accordance with UDF 2.5 (see reference 1: JP 2005-243079 A).
File systems having UDF2.5 relating to rewritable recording media such as BD-REs (Blu-ray Disk Rewritable) makes management information redundant when recording it on a recording medium, and concentrates the managed information in a recording area on the recording medium.
The management information shows where on a recording medium a file exists and what kind of file it is. When metadata (management information) is updated as a result of additional writing for user data on the recording medium, an optical disc drive records the metadata (MD) in a metadata area (a first management area). In addition, in order to make this metadata redundant, the optical disc drive records the metadata file also in a metadata mirror area (a second management area). Backup data the same as the metadata is recorded in the metadata mirror area.
The metadata mirror area is provided separately from the metadata area on the recording medium. For example, conventionally, the metadata area is arranged on an inner circumferential side on an optical disc, while the metadata mirror area is arranged on an outer circumferential side.
Accordingly, even if the meta data area is damaged or deteriorates, the drive can read the metadata from the metadata mirror area and access a target file.
Concentrated placement for management information means recording one piece of management information continuously without dividing it. This enables the optical disc drive to read the management information quickly, so it can access a target file in a short time period.
In addition, a file format having UDF 2.6 relating to a write-once recording medium such as BD-Rs (Blu-ray Disc Recordable) has been proposed. In UDF 2.6, the management information is made redundant like in UDF 2.5.
The UDF 2.6 employs a pseudo over write method (POW: Pseudo Over Write) that enables a write-once recording medium to behave like a rewritable recording medium in relation to an information processing apparatus such as a host computer.
For example, if new metadata is to be recorded after certain metadata is recorded in a metadata area, the new metadata is alternately recorded in a second position next to a first position where the certain metadata has been recorded, instead of recording the new metadata in the position where the certain metadata has been recorded (i.e., overwriting). Link information for the first position and the second position is recorded in a defect list management area provided separately from the metadata area. This link information is likewise provided in the metadata mirror area.
In UDF 2.6, when an optical disc is formatted, the maximum size of the metadata area (e.g., 450-plus MB) is secured, and at the same time, the metadata mirror area having the same capacity as the maximum size of the metadata has to be recorded regardless of the actual size of the metadata recorded in the metadata area, in order to realize the above-described POW method.
As a result, considerable storage capacity is consumed for recording the management information on the recording medium, so the capacity of the area for recording user data will decrease.
In light of the above problem, it is an object of this invention to provide a recording/reproduction apparatus capable of securing a management information backup area on a recording medium without affecting the capacity of a user data area.